About us
About Sleep Time Calculator
Why this site exists
Most sleep advice tells you to "get 8 hours" — but anyone who has woken up groggy after a full eight hours knows the number alone is not the answer. Timing matters: waking at the end of a 90-minute sleep cycle feels completely different from being dragged out of deep sleep in the middle of one. Sleep Time Calculator exists to make that timing trivial to get right.
What we built
The site is a small, focused set of free tools: a sleep time calculator that works out your ideal bedtime or wake-up time from 90-minute cycles, a nap length guide, a sleep debt calculator with a realistic repayment plan, and a jet lag recovery planner that builds a day-by-day adjustment schedule for your trip. Every tool runs entirely in your browser — no sign-up, no downloads, nothing sent to a server.
How we write our content
Our explanations are based on established sleep science: the structure of sleep cycles, sleep inertia, circadian rhythm research, and public-health sleep duration recommendations. Where the science has uncertainty — and it often does — we say so rather than overstate precision. The calculators use well-known averages (a ~90-minute cycle, ~14 minutes to fall asleep), and we label them as estimates, not personal medical guidance.
Our experience promise
The tools work instantly, work on any device, and work without JavaScript for their reference tables. We do not require accounts, we do not track you, and we keep the pages fast and readable. If we ever add analytics or advertising, our Privacy Policy will be updated first.
Corrections and feedback
Found an error in our science or a bug in a calculator? We genuinely want to know. Write to us at [email protected] with the page URL and the detail that needs fixing.